Recently, in accordance with the widespread use of broadband in the mobile communication service, there is an ever increasing demand for high speed and high capacity. In this situation, LTE (Long Term Evolution), which is the next-generation mobile communication system as an alternative to the 3rd generation mobile communication system typified by W-CDMA (Wideband Code Division Multiple Access) and the 3.5th generation mobile communication system, is expected as a standard which leads to the 4th generation mobile communication system.
LTE is a communication standard which is standardized and prescribed by 3GPP (Third Generation Partnership Project), where a plurality of channel widths (1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, or, 20 MHz) is defined by standards, OFDMA (Orthogonal Frequency Division Multiple Access) is used for the downlink, SC-FDMA (Single Carrier Frequency Division Multiple Access) is used for the uplink, and the communication speed of the peak data rate of 100 Mbps or more in the downlink and 50 Mbps or more in the uplink (in either case, the frequency bandwidth is 20 MHz) is a requirement.
Further, in order to further widen the bandwidth and increase communication speed, LTE-Advanced (hereinafter referred to as “LTE-A”) using broadband including the system band, which is an allowable bandwidth for reception of LTE, is being standardized.
LTE-A is characterized in that, in order to be compatible with LTE and flexibly widen the bandwidth, by adopting two techniques of: a technique of upgrading MIMO (Multiple Input Multiple Output) of the spatial multiplexing technique; and a technique of widening the frequency bandwidth (Carrier Aggregation: CA) as a means of achieving wider bandwidth that bundles the frequency blocks (a channel bandwidth of maximum 20 MHz) for LTE called the component carrier (CC). Then, hybrid automatic repeat request (HARQ) or adaptive modulation channel encoding corresponding to radio wave environment is performed for each component carrier, and thus efficiency increases and transmission speed is improved (refer to Non-Patent Document 1 for further detail).